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Re: [Qemu-devel] QEMU event loop optimizations
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] QEMU event loop optimizations |
Date: |
Mon, 8 Apr 2019 12:42:00 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 |
On 05/04/19 18:33, Sergio Lopez wrote:
>> - qemu_bh_schedule_nested should not be necessary since we have
>> ctx->notify_me to also avoid the event_notifier_set call. However, it
>> is possible to avoid the smp_mb at the beginning of aio_notify, since
>> atomic_xchg already implies it. Maybe add a "static void
>> aio_notify__after_smp_mb"?
> try_poll_mode() is called with ctx->notify_me != 0, so we get at least
> one event_notifier_set() call while working in polling mode.
Right, though then there is the idea of making ctx->notify_me and
ctx->notified bitmasks, where bit 0 is "BH ready" and bit 1 is "poll()
parameters changed". try_poll_mode() cares about the latter, but does
not need event_notifier_set() for BH ready.
Paolo